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Tue, 5 Aug 2025 17:36:11 +0000 (GMT) From: "Alim Akhtar" To: "'Manivannan Sadhasivam'" Cc: "'Konrad Dybcio'" , "'Krzysztof Kozlowski'" , "'Ram Kumar Dwivedi'" , , , , , , , , , , , , , , In-Reply-To: Subject: RE: [PATCH 2/3] arm64: dts: qcom: sa8155: Add gear and rate limit properties to UFS Date: Tue, 5 Aug 2025 23:06:10 +0530 Message-ID: <061c01dc062f$70ec34b0$52c49e10$@samsung.com> Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Content-Language: en-us Thread-Index: AQGIhTOigFb9OSA/zLmmRAowhNFqCwJZOa1wAh4tdyIBxgZwxgI/ArKTAmrI7FMCp5bdBAEsJt2OAdY+bWECqijPQgIPv58TtFD7bNA= X-CMS-MailID: 20250805173614epcas5p3729afd6d84cb56236fe117f902422a09 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P cpgsPolicy: CPGSC10-542,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250805170638epcas5p4cb0cc78c5b5d77072cec547380b9f03d References: <2a3c8867-7745-4f0a-8618-0f0f1bea1d14@kernel.org> <1701ec08-21bc-45b8-90bc-1cd64401abd8@kernel.org> <2nm7xurqgzrnffustrsmswy2rbug6geadaho42qlb7tr2jirlr@uw5gaery445y> <11ea828a-6d35-4ac6-a207-0284870c28fc@oss.qualcomm.com> <061b01dc062d$25c47800$714d6800$@samsung.com> > -----Original Message----- > From: 'Manivannan Sadhasivam' > Sent: Tuesday, August 5, 2025 10:52 PM > To: Alim Akhtar > Cc: 'Konrad Dybcio' ; 'Krzysztof > Kozlowski' ; 'Ram Kumar Dwivedi' > ; avri.altman=40wdc.com; > bvanassche=40acm.org; robh=40kernel.org; krzk+dt=40kernel.org; > conor+dt=40kernel.org; andersson=40kernel.org; konradybcio=40kernel.org; > James.Bottomley=40hansenpartnership.com; martin.petersen=40oracle.com; > agross=40kernel.org; linux-arm-msm=40vger.kernel.org; linux- > scsi=40vger.kernel.org; devicetree=40vger.kernel.org; linux- > kernel=40vger.kernel.org > Subject: Re: =5BPATCH 2/3=5D arm64: dts: qcom: sa8155: Add gear and rate = limit > properties to UFS >=20 > On Tue, Aug 05, 2025 at 10:49:45PM GMT, Alim Akhtar wrote: > > > > > > > -----Original Message----- > > > From: Konrad Dybcio > > > Sent: Tuesday, August 5, 2025 10:36 PM > > > To: Manivannan Sadhasivam > > > Cc: Krzysztof Kozlowski ; Ram Kumar Dwivedi > > > ; alim.akhtar=40samsung.com; > > > avri.altman=40wdc.com; bvanassche=40acm.org; robh=40kernel.org; > > > krzk+dt=40kernel.org; conor+dt=40kernel.org; andersson=40kernel.org; > > > konradybcio=40kernel.org; James.Bottomley=40hansenpartnership.com; > > > martin.petersen=40oracle.com; agross=40kernel.org; linux-arm- > > > msm=40vger.kernel.org; linux-scsi=40vger.kernel.org; > > > devicetree=40vger.kernel.org; linux-kernel=40vger.kernel.org > > > Subject: Re: =5BPATCH 2/3=5D arm64: dts: qcom: sa8155: Add gear and r= ate > > > limit properties to UFS > > > > > > On 8/5/25 6:55 PM, Manivannan Sadhasivam wrote: > > > > On Tue, Aug 05, 2025 at 03:16:33PM GMT, Konrad Dybcio wrote: > > > >> On 8/1/25 2:19 PM, Manivannan Sadhasivam wrote: > > > >>> On Fri, Aug 01, 2025 at 11:12:42AM GMT, Krzysztof Kozlowski wrote= : > > > >>>> On 01/08/2025 11:10, Ram Kumar Dwivedi wrote: > > > >>>>> > > > >>>>> > > > >>>>> On 01-Aug-25 1:58 PM, Manivannan Sadhasivam wrote: > > > >>>>>> On Thu, Jul 24, 2025 at 09:48:53AM GMT, Krzysztof Kozlowski > wrote: > > > >>>>>>> On 22/07/2025 18:11, Ram Kumar Dwivedi wrote: > > > >>>>>>>> Add optional limit-hs-gear and limit-rate properties to the > > > >>>>>>>> UFS node to support automotive use cases that require > > > >>>>>>>> limiting the maximum Tx/Rx HS gear and rate due to hardware > constraints. > > > >>>>>>> > > > >>>>>>> What hardware constraints? This needs to be clearly > documented. > > > >>>>>>> > > > >>>>>> > > > >>>>>> Ram, both Krzysztof and I asked this question, but you never > > > >>>>>> bothered to reply, but keep on responding to other comments. > > > >>>>>> This won't help you to get this series merged in any form. > > > >>>>>> > > > >>>>>> Please address *all* review comments before posting next > iteration. > > > >>>>> > > > >>>>> Hi Mani, > > > >>>>> > > > >>>>> Apologies for the delay in responding. > > > >>>>> I had planned to explain the hardware constraints in the next > > > patchset=E2=80=99s=20commit=20message,=20which=20is=20why=20I=20didn= =E2=80=99t=20reply=20earlier.=0D=0A>=20>=20>=20>>>>>=0D=0A>=20>=20>=20>>>>>= =20To=20clarify:=20the=20limitations=20are=20due=20to=20customer=20board=20= designs,=0D=0A>=20>=20>=20>>>>>=20not=20our=0D=0A>=20>=20>=20SoC.=20Some=20= boards=20can't=20support=20higher=20gear=20operation,=20hence=20the=20need= =0D=0A>=20>=20>=20for=20optional=20limit-hs-gear=20and=20limit-rate=20prope= rties.=0D=0A>=20>=20>=20>>>>>=0D=0A>=20>=20>=20>>>>=0D=0A>=20>=20>=20>>>>= =20That's=20vague=20and=20does=20not=20justify=20the=20property.=20You=20ne= ed=20to=0D=0A>=20>=20>=20>>>>=20document=20instead=20hardware=20capabilitie= s=20or=20characteristic.=20Or=0D=0A>=20>=20>=20>>>>=20explain=20why=20they= =20cannot.=20With=20such=20form=20I=20will=20object=20to=20your=0D=0A>=20>= =20>=20>>>>=20next=0D=0A>=20>=20>=20patch.=0D=0A>=20>=20>=20>>>>=0D=0A>=20>= =20>=20>>>=0D=0A>=20>=20>=20>>>=20I=20had=20an=20offline=20chat=20with=20Ra= m=20and=20got=20clarified=20on=20what=20these=0D=0A>=20>=20>=20>>>=20proper= ties=0D=0A>=20>=20>=20are.=0D=0A>=20>=20>=20>>>=20The=20problem=20here=20is= =20not=20with=20the=20SoC,=20but=20with=20the=20board=20design.=0D=0A>=20>= =20>=20>>>=20On=20some=20Qcom=20customer=20designs,=20both=20the=20UFS=20co= ntroller=20in=20the=0D=0A>=20>=20>=20>>>=20SoC=20and=20the=20UFS=20device= =20are=20capable=20of=20operating=20at=20higher=20gears=20(say=0D=0A>=20G5)= .=0D=0A>=20>=20>=20>>>=20But=20due=20to=20board=20constraints=20like=20poor= =20thermal=20dissipation,=0D=0A>=20>=20>=20>>>=20routing=20loss,=20the=20bo= ard=20cannot=20efficiently=20operate=20at=20the=20higher=0D=0A>=20speeds.= =0D=0A>=20>=20>=20>>>=0D=0A>=20>=20>=20>>>=20So=20the=20customers=20wanted= =20a=20way=20to=20limit=20the=20gear=20speed=20(say=20G3)=0D=0A>=20>=20>=20= >>>=20and=20rate=20(say=20Mode-A)=20on=20the=20specific=20board=20DTS.=0D= =0A>=20>=20>=20>>=0D=0A>=20>=20>=20>>=20I'm=20not=20necessarily=20saying=20= no,=20but=20have=20you=20explored=20sysfs=20for=20this?=0D=0A>=20>=20>=20>>= =0D=0A>=20>=20>=20>>=20I=20suppose=20it=20may=20be=20too=20late=20(if=20the= =20driver=20would=20e.g.=20init=20the=0D=0A>=20>=20>=20>>=20UFS=20at=20max= =20gear/rate=20at=20probe=20time,=20it=20could=20cause=20havoc=20as=20it=0D= =0A>=20>=20>=20>>=20tries=20to=20load=20the=20userland)..=0D=0A>=20>=20>=20= >>=0D=0A>=20>=20>=20>=0D=0A>=20>=20>=20>=20If=20the=20driver=20tries=20to= =20run=20with=20unsupported=20max=20gear=20speed/mode,=0D=0A>=20>=20>=20>= =20it=20will=20just=20crash=20with=20the=20error=20spit.=0D=0A>=20>=20>=0D= =0A>=20>=20>=20OK=0D=0A>=20>=20>=0D=0A>=20>=20>=20just=20a=20couple=20relat= ed=20nits=20that=20I=20won't=20bother=20splitting=20into=0D=0A>=20>=20>=20s= eparate=20emails=0D=0A>=20>=20>=0D=0A>=20>=20>=20rate=20(mode?=20I'm=20seei= ng=20both=20names)=20should=20probably=20have=20dt-bindings=0D=0A>=20>=20>= =20defines=20while=20gear=20doesn't=20have=20to=20since=20they're=20called= =20G=0D=0A>=20>=20>=20anyway,=20with=20the=20bindings=20description= =20strongly=20discouraging=20use,=0D=0A>=20>=20>=20unless=20absolutely=20ne= cessary=20(e.g.=20in=20the=20situation=20we=20have=20right=0D=0A>=20>=20>= =20there)=0D=0A>=20>=20>=0D=0A>=20>=20>=20I'd=20also=20assume=20the=20code= =20should=20be=20moved=20into=20the=20ufs-common=20code,=0D=0A>=20>=20>=20r= ather=20than=20making=20it=20ufs-qcom=20specific=0D=0A>=20>=20>=0D=0A>=20>= =20>=20Konrad=0D=0A>=20>=20Since=20this=20is=20a=20board=20specific=20const= rains=20and=20not=20a=20SoC=20properties,=20have=20an=0D=0A>=20option=20of= =20handling=20this=20via=20bootloader=20is=20explored?=0D=0A>=20=0D=0A>=20B= oth=20board=20and=20SoC=20specific=20properties=20*should*=20be=20described= =20in=20devicetree=0D=0A>=20if=20they=20are=20purely=20describing=20the=20h= ardware.=0D=0A>=20=0D=0AAgreed,=20what=20I=20understood=20from=20above=20co= nversation=20is=20that,=20we=20are=20try=20to=20solve=20a=20very=20*specifi= c*=20board=20problem=20here,=20=0D=0Athis=20does=20not=20looks=20like=20a= =20generic=20problem=20to=20me=20and=20probably=20should=20be=20handled=20w= ithin=20the=20specific=20driver.=0D=0A=0D=0A>=20-=20Mani=0D=0A>=20=0D=0A>= =20--=0D=0A>=20=E0=AE=AE=E0=AE=A3=E0=AE=BF=E0=AE=B5=E0=AE=A3=E0=AF=8D=E0=AE= =A3=E0=AE=A9=E0=AF=8D=20=E0=AE=9A=E0=AE=A4=E0=AE=BE=E0=AE=9A=E0=AE=BF=E0=AE= =B5=E0=AE=AE=E0=AF=8D=0D=0A=0D=0A